Researchers have completed the first comprehensive database of freshwater species on Australian islands. The results of the research have been published in Diversity and Distributions journal.

The University of Queensland Biodiversity Research Group study found that of 567 islands with freshwater habitats, 197 contained 102 frog species, amounting to almost half of all known Australian frog species. Ninety-five freshwater fish species were found, 11 of which were vulnerable or endangered.

The study found K’gari, the world’s largest sand island, had the most frog and freshwater species of all Australian islands.

Researcher Sam Ho said he was shocked by the number of frog species and hoped the information would be used to conserve those at risk of extinction on the mainland.

Biodiversity Research Group Head, Professor Salit Kark, said the role of islands as refuges for endangered species meant they had often been “extinction hubs” where the last remaining individuals of a species had been lost, including the King Island emu and the Norfolk Island kaka.

Professor Kark said the rich biodiversity on K’gari highlighted the value of its World Heritage status.

“I think it should be really one of the flagship islands that we’re further studying and investing in,” she said.

Mr Ho and his colleagues did a year-long search of scientific databases, journals and government reports, boosted by the Atlas of Living Australia, Australia’s largest biodiversity database fed by citizen-science platforms such as iNaturalist.

The data collected by growing numbers of citizen scientists was a boon for the researchers, but Professor Kark said there was a “trade-off” with the impacts of the increasing numbers of visitors.

“I think it’s really that balance that needs to be thought about quite carefully, and we must have more data both on the [visitor] impacts but also for native and introduced species,” she said.

Experts say the data shows stronger protections for K’gari’s biodiversity – possibly including a cap on visitor numbers – are needed. They say that without improved management, ever-increasing tourist numbers – including the crowds expected during the Brisbane Olympics in 2032 – are putting the island’s World Heritage status at risk.

Adapted from an article first published on 10 September 2025 by James Taylor, ABC Wide Bay